LOANS - Consumer Troubled Debt Restructurings (Details) - Consumer $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) loan	Sep. 30, 2021 USD ($) loan	Sep. 30, 2022 USD ($) loan	Sep. 30, 2021 USD ($) loan
Loans receivable
Period within which default occurred post-modification			1 year
Number of days past due, non-accrual status			60 days
In North America offices
Loans receivable
Number of loans modified | loan	46,810	34,233	125,453	131,084
Post-modification recorded investment	$ 278.0	$ 211.0	$ 763.0	$ 831.0
TDR loans in payment default	$ 69.0	$ 72.0	$ 204.0	$ 250.0
In North America offices | Residential mortgages
Loans receivable
Number of loans modified | loan	235	285	860	955
Post-modification recorded investment	$ 58.0	$ 49.0	$ 195.0	$ 169.0
Average interest rate reduction	0.00%	1.00%	0.00%	0.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 1.8	$ 3.8	$ 3.7	$ 10.7
TDR loans in payment default	6.0	10.0	23.0	43.0
In North America offices | Residential mortgages | New OCC guidance
Loans receivable
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 1.8	$ 1.6	$ 3.7	$ 4.1
In North America offices | Home equity loans
Loans receivable
Number of loans modified | loan	117	33	324	145
Post-modification recorded investment	$ 14.0	$ 2.0	$ 30.0	$ 11.0
Average interest rate reduction	0.00%	0.00%	0.00%	0.00%
TDR loans in payment default	$ 1.0	$ 1.0	$ 3.0	$ 8.0
In North America offices | Credit cards
Loans receivable
Number of loans modified | loan	46,326	33,746	123,886	129,129
Post-modification recorded investment	$ 203.0	$ 159.0	$ 533.0	$ 640.0
Average interest rate reduction	18.00%	18.00%	18.00%	17.00%
TDR loans in payment default	$ 62.0	$ 60.0	$ 178.0	$ 196.0
In North America offices | Personal, small business and other
Loans receivable
Number of loans modified | loan	132	169	383	855
Post-modification recorded investment	$ 3.0	$ 1.0	$ 5.0	$ 11.0
Average interest rate reduction	7.00%	5.00%	5.00%	3.00%
TDR loans in payment default	$ 0.0	$ 1.0	$ 0.0	$ 3.0
In offices outside North America
Loans receivable
Number of loans modified | loan	4,266	23,869	14,288	82,080
Post-modification recorded investment	$ 27.0	$ 142.0	$ 88.0	$ 505.0
TDR loans in payment default	$ 6.0	$ 74.0	$ 22.0	$ 251.0
In offices outside North America | Residential mortgages
Loans receivable
Number of loans modified | loan	172	451	465	1,448
Post-modification recorded investment	$ 6.0	$ 22.0	$ 16.0	$ 74.0
Average interest rate reduction	0.00%	0.00%	0.00%	0.00%
TDR loans in payment default	$ 2.0	$ 9.0	$ 9.0	$ 31.0
In offices outside North America | Credit cards
Loans receivable
Number of loans modified | loan	3,519	16,082	11,981	58,978
Post-modification recorded investment	$ 15.0	$ 71.0	$ 50.0	$ 267.0
Average interest rate reduction	27.00%	15.00%	24.00%	14.00%
TDR loans in payment default	$ 3.0	$ 36.0	$ 10.0	$ 133.0
In offices outside North America | Personal, small business and other
Loans receivable
Number of loans modified | loan	575	7,336	1,842	21,654
Post-modification recorded investment	$ 6.0	$ 49.0	$ 22.0	$ 164.0
Average interest rate reduction	8.00%	9.00%	8.00%	10.00%
TDR loans in payment default	$ 1.0	$ 29.0	$ 3.0	$ 87.0
Deferred principal | In North America offices
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In North America offices | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In North America offices | Home equity loans
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0
Deferred principal | In North America offices | Credit cards
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In North America offices | Personal, small business and other
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In offices outside North America
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In offices outside North America | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In offices outside North America | Credit cards
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Deferred principal | In offices outside North America | Personal, small business and other
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In North America offices
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In North America offices | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In North America offices | Home equity loans
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In North America offices | Credit cards
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In North America offices | Personal, small business and other
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In offices outside North America
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In offices outside North America | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In offices outside North America | Credit cards
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Contingent principal forgiveness | In offices outside North America | Personal, small business and other
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In North America offices
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In North America offices | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In North America offices | Home equity loans
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In North America offices | Credit cards
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In North America offices | Personal, small business and other
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In offices outside North America
Loans receivable
Post-modification recorded investment	1.0	4.0	2.0	16.0
Principal forgiveness | In offices outside North America | Residential mortgages
Loans receivable
Post-modification recorded investment	0.0	0.0	0.0	0.0
Principal forgiveness | In offices outside North America | Credit cards
Loans receivable
Post-modification recorded investment	0.0	2.0	1.0	10.0
Principal forgiveness | In offices outside North America | Personal, small business and other
Loans receivable
Post-modification recorded investment	$ 1.0	$ 2.0	$ 1.0	$ 6.0